This project attempts to bridge basic and clinical science by examining how the basal ganglia control movement, and how they malfunction in Parkinson's disease. It allows the candidate, whose background is in normal basal ganglia anatomy and physiology, gain experiment in functional MRI (fMRI) imaging and the study of movement disorders. Only recently has it become possible to image the basal ganglia with fMRI. Our preliminary results show reliable, somatotopic basal ganglia activation by movement, pronounced left dominance in basal ganglia activation, and increased basal ganglia activation during bilateral compared to unilateral tasks. We how hypothesize (1) that the basal ganglia are important for sequencing or inhibition of competing movements. (2) Parkinsonians have altered movement-related activation in the striatum and cortex which reflects a disruption of his inhibition. (3) Therapies for Parkinson's disease such as dopamine agonists and globus pallidus lesions (pallidotomy)partially normalize this altered activation, but in different ways. The project would advance the basic neuroscience of motor processing. For instance, pallidotomy is a unique chance to measure the functional effects of precisely placed lesions in the basal ganglia circuit. It would also have direct clinical implications. There is currently no reliable diagnostic test for Parkinson's disease. FMRI might in the future prove to be such a test. FMRI might also allow independent investigation of Parkinsonian, such as patients with dyskinesias, who would benefit more from certain treatments. It may help monitor the efficacy of treatment in individual patients. Finally, better understanding of how the basal ganglia process motor inputs may provide clues how they process other inputs, chiefly cognitive and limbic This is of extreme interest because of the growing evidence for a basal ganglia role in learning and reward, and in schizophrenia, obsessive-compulsive disorder, and drug addiction.